The FTIR spectra of ZrO2 and KOH(32%)/ZrO2-5 catalysts were also examined (Fig. 3). The spectra of ZrO2 and KOH(32%)/ZrO2-5 indicate sharp peaks at 2450 and 750/cm, respectively. New peaks at 1550 and 1350/cm on KOH(32%)/ZrO2-5 could be attributed to K–O and K–O–Zr bonds, respectively. The band between 3000–3300/cm regions could also be partly assigned to the stretching vibration of Zr–O–K groups [11] in which K+ ions could have replaced the protons of isolated hydroxyl groups to form Zr–O–K in the activation process.